Choose which reasoning process is shown in the following example. Explain your answer. n(n + 1) It can be shown that 1 + 2+ 3+ ... + n= 2 This formula can be used to conclude that the sum of the first 700 numbers, 1 + 2 + 3+ ... + 700, is the following. 700(700 + 1) 700(701) 2 2 = 350(701), or 245,350